did you made calculus about resulting power, as tool to justify increase of rail voltage and decrease of Iq?
if you wanted increased power, you need to both increase rail voltage and Iq
if not, as you did, very possible result is decrease in power, while decreased THD, due to rail voltage going up
if you wanted increased power, you need to both increase rail voltage and Iq
if not, as you did, very possible result is decrease in power, while decreased THD, due to rail voltage going up
These numbers in my previous post just represents the somewhat middle of the road of the now possible potentiometer adjustment ranges.
My goal is just really great sounding amps, i really do not need more power, say in reality - no more than around 15W/channel is actually needed.
I plan to set up my Focusrite Solo and REW for THD visualisation and guidance further towards a good tuning of the amps.
But ultimately, the main thing that counts for me is the actual musicality and sound, not Max Power or Min THD. But these things are of course of real importance too. 🙂
But if i understand you right, your advice is turn down the middle point voltage a little, and turn up bias a little?
My goal is just really great sounding amps, i really do not need more power, say in reality - no more than around 15W/channel is actually needed.
I plan to set up my Focusrite Solo and REW for THD visualisation and guidance further towards a good tuning of the amps.
But ultimately, the main thing that counts for me is the actual musicality and sound, not Max Power or Min THD. But these things are of course of real importance too. 🙂
But if i understand you right, your advice is turn down the middle point voltage a little, and turn up bias a little?
you got it all
Iq - as much you really need oooooomph for your room/speakers/ears
voltage across SIT - what gives you most foot-tapping; start from Urail/2 and go up; stop where you like it most
1. I used arctic silver on all mating surfaces.
2. Loc-tite on all heat exposed screws.
3. Achieved dead silent operation after moving Mu boards an 1”. My shop is electrically a very noisy environment so this was great.
4. To give you some scale at the enormity of this chassis, those are rubber pucks for large furniture.
After a listening session last night I was struck by how much it its a cross between the XA-25 (IXYS puck providing a small part of the gain?) and my P-P Kinkless 88. Both of these amps are a reference for me so I would say it certainly sits on that podium.
There’s a wonderful space and openness to the amp while providing that wonderful richness of tone. What was also shocking was that it fully opened the recording venue with the sound a triode, but the drive of SS.
I have lots of comparisons to make, however, I think it’s already how it will do: So far, it’s spectacular.
2. Loc-tite on all heat exposed screws.
3. Achieved dead silent operation after moving Mu boards an 1”. My shop is electrically a very noisy environment so this was great.
4. To give you some scale at the enormity of this chassis, those are rubber pucks for large furniture.
After a listening session last night I was struck by how much it its a cross between the XA-25 (IXYS puck providing a small part of the gain?) and my P-P Kinkless 88. Both of these amps are a reference for me so I would say it certainly sits on that podium.
There’s a wonderful space and openness to the amp while providing that wonderful richness of tone. What was also shocking was that it fully opened the recording venue with the sound a triode, but the drive of SS.
I have lots of comparisons to make, however, I think it’s already how it will do: So far, it’s spectacular.
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I am having fun, trial and error initial experimenting with the REW and Focusrite Solo rev3 setup. 🙂
Does this seem somewhat reasonable? The 50hz bump seems a bit high?
This picture above is with the amplifier completely turned off.
This screenshot above is with the amp running at 1W and 8R.
Does this seem somewhat reasonable? The 50hz bump seems a bit high?
This picture above is with the amplifier completely turned off.
This screenshot above is with the amp running at 1W and 8R.
How sensitive are the speakers and is there any audible hum with ear close to speaker units?
Often some higher harmonic hum-components are audible in the tweeter with ear close to it if amp has a "hum-problem".
I have experienced this many times but been able to cure it 🙂
Often some higher harmonic hum-components are audible in the tweeter with ear close to it if amp has a "hum-problem".
I have experienced this many times but been able to cure it 🙂
No audiable hum what so ever with the amp input RCA shorted, and with the ear against the small build/test bench speakers. KEF HTS3001SE 86 dB/w/m. Thats good!
But The hum is audiable when the test rig is on and attatched to the amp. It seems no big deal then, but the test rig is sensitive to touch. A hand on the outside chassi on the Focusrite or on the plastic cables makes the 50hz bump stronger. A little bit of a mystery. 🙂
But The hum is audiable when the test rig is on and attatched to the amp. It seems no big deal then, but the test rig is sensitive to touch. A hand on the outside chassi on the Focusrite or on the plastic cables makes the 50hz bump stronger. A little bit of a mystery. 🙂
Just testing. 🙂
I have activated the function to display phase of the distorsion components. Here as an example -89 deg for the 2nd. And here is the FFT-picture of 10W 8R. At 42,6V midpoint node voltage and 2,23A bias.
I have activated the function to display phase of the distorsion components. Here as an example -89 deg for the 2nd. And here is the FFT-picture of 10W 8R. At 42,6V midpoint node voltage and 2,23A bias.
Right now i run it without ground, with balanced output and input: Only hot and cold, T, R but not ground/S connected. As previously advised in a guide i have read.
It might be worth try to ground the midpoint in my attenuator to ground/S just for fun?
But first i have to eat some lunch! 🙂
It might be worth try to ground the midpoint in my attenuator to ground/S just for fun?
But first i have to eat some lunch! 🙂
Connect the amp to a source that is grounded and test again, that mains energy at 50Hz is very high. In my shop I get all kinds of noise issues because of the lights and two freezers near plugged into the mains just a few feet away. As soon as I go to my listening room on the other side of the house it all goes away.
I run my test with an Ipad, so same problem, no good ground to drain at the source.
Or maybe just
The DUT isn’t balanced in right?
Or maybe just use hot and shield straight from focusrite to rca and an attenuated grounded speaker output to hot and pin 1 on the same.
The DUT isn’t balanced in right?
50Hz is testing setup mess
100Hz is PSU ripple combined with circuit PSSR
100Hz is PSU ripple combined with circuit PSSR
I use a standalone oscillator now but when I used the Focusrite signal I found that using a TS plug worked best. So with a TSR plug connect the S and R together, connect the T to RCA positive, and the S and R together to ground.
Edit: You may have to adjust resistor values. I use a voltage divider in my setup: https://www.akitika.com/documents/BuildingTheAttenuatorRev4.pdf
Edit: You may have to adjust resistor values. I use a voltage divider in my setup: https://www.akitika.com/documents/BuildingTheAttenuatorRev4.pdf
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